Preparation of chlorine-containing copper phthalocyanines



United States Patent O M PREPARATION OF CHLORINE-CONTAINING COPPER PHTHALOCYANINES Julius Jackson, Westfield, NJ., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Application February 5, 1957 Serial No. 638,224

9 claims. (ci. 26o-314.5)

This invention relates to a process for the preparation of chlorine-containing copper phthalocyanine pigments which are crystal stable and highly resistant to occulation in coating compositions.

Phthalocyanine pigments, and copper phthalocyanine in particular, are well known products which are described in many patents and other publications. There are two widely used methods of preparation. In the one method, a phthalic acid derivative, such as phthalic anhydride, is reacted with urea and a metal salt, such as copper chloride, usually in the presence of an inert diluent liquid at temperatures in the range of about 190 C.220 C. In the other method, with which this invention is concerned, an aromatic dinitrile, such as phthalonitrile, is reacted with a metal salt, such as a copper chloride, at a temperature 'in the range of 180 C.-300 C. As in the iirst process, it is common to carry out this reaction in the presence of an inert diluent liquid although both processes may be carried out in the absence of dluent liquid. The diluent liquid may be removed'by simple ltration, by steam distillation, or by simple decantation after the pigment has been treated to promote settling. This is usually followed by a conventional drying step. i Y

After drying, pigments obtained by either of these processes are usually subjected to some form of particle size reduction to develop their full pigmentary properties.

Various methods of achieving this end have been proposed and widely used. The oldest method is essentially a chemical process in that the pigment is reacted Awith concentrated sulfuric acid to, form a sulfate which is then dissolved in additional concentrated Vsulfuric acid and reprecipitatedby drowning the solution. in a large volurne of water;` I-n contrast to this essentially chemical methodof particle size reduction, there have been proposed a number of methods which areV essentially mechanical in character in that the particle size reduction is brought about by various types of milling operations. The pigment may be charged to a ball mill together with a relatively large amount of a crystalline material, such as common salt, and after a suitable milling period with relatively large steel balls or similar milling aids, the pigment is isolated by extraction of the water-soluble salt and then puried, usually with dilute acid solution. In another process of like character, the pigment is milled in a ball mill in an organic liquid, such as acetone, preferably using small (i1;" diameter) steel shot as the grinding aid. The acetone is removed by' steam distillation and a similar purication by extraction with dilute acid is usually used.

There are two problems concerning the use of phthalocyanine pigments which have been widely recognized and which have received much attention in published art. The rst of these is crystal stability. Some phthalocyanine pigments have been found to grow relatively large crystals when exposed to certain organic solvents, such as aromatic hydrocarbons, which are often used in 2,933,505, Patented Apr.v 19, 1960- This crystal growth reverses the effect of the particle size reduction and results in a marked loss in the tinctorial powers of the pigment. It has also been found that phthalocyanine pigments are not only subject to crystal growth but that they are capable of existing in two crystal phases. One phase which has been arbitrarily designated the alpha phase in much published literature (see FIAT Report 1313 vol. 3, p. 447; also U.S. Patent 2,556,726) is relatively red in hue and quite prone to change to the beta crystal phase which is much greener in hue. By the selection of suitable conditions, it is possible to obtain the beta phase in a small particle size which is resistant to crystal growth and is thereforez regarded as crystal stable. In order to obtain the redder shade (the alpha phase) of pigment in a crystal stabley form, it has been common practice to introduce a small amount (from 3% to 6%) of chlorine into the pigment.

Such partially chlorinated products may be obtained in the phthalic anhydride-urea synthesis by the use of a small amount of a chlorinated phthalic acid derivative in the synthesis. ried out with a copper chloride at temperatures above 180 C., chlorine is introduced into the copper phthalo= cyanine molecule. Thus, in the conventional operating range of 190 C.-220 C. for the phthalonitrile synthesis,

the use of cuprous chloride has resulted in the introduction of about half of the theoretical amount of chlorine to be found in a monochloro copper phthalocyanine, whereas the use of cupric chloride in the synthesis has resulted in the formation of a monochloro copper phthalocyanine.

In addition to the problem of crystal stability for which solutions are shown above, phthalocyanine pigments can present a second problem which is known as ,occulation. This problem becomes apparent when a coating composition containing a occulating phthalocyanine pigment is applied by diiferent methods, and it manifests it self as variations in color which seem to depend upon the degree to which work is done on the coating composition during its application to a surface or during the drying of the lm.' Thus," a paint lm which is applied by dipping,'whereas the rest of the body is coated by spray-, ing. Another diculty due to ilocculation arises* when paints are applied by brushing since lapped areasnwhere:

dipping or pouring is frequently much lighter in colorthan the same paint lm applied by spraying. This situation is encountered in the manufacture of automobiles whereincertain items, such as fenders, may be coated by the partially set film is rebrushed frequently show up darker than the rest' of the surface.' Pigments which have been stabilized against crystal growth bythe intro' duction of chlorine into the molecule seem to be especial? ly subject to this phenomenon of flocculation, and this invention is designed to overcome the flocculation tendency of such chlorine-containing copper phthalocyanine' pigments.

It is the object of this invention to prepare a chlorine-l containing, flocculation-resistant copper phthalocyanine pigment exhibiting the tinctorial characteristics of th alpha crystal phase.

The objects of this invention are accomplished by .syi1' thesizing copper phthalocyanine-coloring matters from an' o-arylene dinitrile and a copperchloride in the presence of from .015 to .15 mol of an aromatic tertiary nitrogenl base such as pyridine per mol of the o-arylene dinitrile.

The copper phthalocyanine so prepared is then reduced to pigment particle size by mechanical means to produce aV connection with the formulation of coating compositions above in conjunction with a particle size reduction by If the phthalonitrile synthesis is car-' mechanical-means.

J Chemical means for reducing particle size destroy the occ-ulation resistance.

In a preferred embodiment, the invention is carried out by heating phthalonitrile and a copper chloride at a temperature above 180' C. but below the temperature' at which the phthalonitrile will carbonize in the presence of from .015 to .15 mol of pyridine per mol of phthalonitrile.V The heating is continued until a blue solid coloring matter is obtained. This material is then recovered and reduced to pigment particle size by a milling operation, preferably in a ball mill. After the miiiing operation, and purication of thepigment by conventional Vextraction in dilute acid solution, there is obtainedaocculation-resistant, crystal-stable, chlorine-containing phth.alocyanineV pigment: Y

In anotherpreferred embodimentofYV the invention,

l'ahthalonitrileY and Va mixture of' cuprous chloridey and cupric chloride/are reacted-tin kerosene asA 'an' inertv diluentandin the presenceof'r about .02S- mol of? pyridine` per mol of'phthalonitrile together with a1 smallamount of ammonium molybdateat a temperature of about 2004" C.

The 'pigment is-4 preferably isolated from the kerosene by addingconcentrated sulfuric acid, decanting offthe kerosene, hydrolyzing the phthalocya'nine sulfate and" neutralizing with an alkali after` which the pigment isiltcred from, therliquid and dried.v The crude. pigment is'then ground in a ball mill with "acetone` using steel shot as the grinding aid after'the manner of U.S. Patent 2556,- Y

727. Grinding isv followed by removal of the acetone, extraction in diluteV acid, iiltering, Washing and' drying.

VThe resulting product is` a chlorine-containing phthalo-r cyanine which` is crystal stablel and highly resistant to` occulation. Y

In another embodiment of this-invention, the-copper chloride and the pyridine may be premixed and reacted before beingY commingled and heated with the phthalonitrile-inthe main synthesis'reaction. This'procedure; is exempliied in vdetail byI Example VI 'which follows.

' Theffollovving examples illustrate this invention in its-f variousimanifestationsin detail. Unless'otherwise-stated; alll parts-are given-'in terms offpartsby weight.

Example 4l Thelfollowing-ingredients are charged to a well-agitated reaetorequipped-'with an air-cooled refiuxcondenser. and

arran'geclfor external heatingz' 12.8 parts phthalonitrile (1 mol)- 7,1 partsupric chloride anhydrous; (0.053,` mol) 20.8 parts cupious chloride anhydrous (012.1, mol) 0,7'v partvammonium rnolybdateY ztofnartsryridine (acumen.

3,10 parts deodorized kerosene The. mixture; is heated-V with good agitation to about: 2059 C. over a period of about 30'minutesand: held at.

205 C.'210 C. for about 4 hours.` It is then cooledto aboutf 150 C. and 310 parts of 98% H2SO4 is added slowly. The mixture isistirred for a short time and then the agitator is stopped, whereupon the kerosene Viloats to the surface and is decanted. The solid remaining is added to a mixture of 1000 parts of Water and 1000 parts of ice to which, about 270 parts of sodium hydroxide isithen added'to make the slurry alkaline. The alkaline slurry thus obtained is heated to the boil and'boiledtorA 11,6', hours.- It is ltered; Washedfreeof soluble Vsalts'and driedf'at 120 C. for about'l-hours until'free of'kerosene.- About l42'parts of a'crude copper phthalocyaninev i tonesT removed bysteanr distillation; andv the resulting This'mill is then aqueous slurry is extracted with hot Idilute (Li-5%) sulfuric acid. It is then ltered, Washedrfree of soluble salts,

dried andY pulverized to give a blue copper phthalocyanine pigment predominately'in the alpha phase which is crystal Vstable and highly resistant to ilocculationV when dispersed in a coatingY compositionV vehicle;Y

Example II The synthesis process of' Example lisf repeated except that 630 parts of trichlorobenzene is used instead of the deodoriz'ed kerosene: Sincef trichiorobenzeneehasf a high density, the separation ofthe liquidsafter the addition of the sulfuric acid..is.less elicienuhence, in this case, itis preferred to hydrolyze the sulfate with Water and neutralize with sodium lhydroxide and to thenY remove the trichlorobenzeneby steaml distillation. The crude productzhasisnbstantially Athev sanfte7 properties* tls-the prodiuctV of'EXanlple. IV except thatrthe chlorine: content is be'- tween 3.0% and 3.5%'. milling` iny acetone, thezproductisan intensebluecopper phthalocyanineV pigment of which over.` is. in, the alpha ,erystal..phase',A and pigment exhibits', the. typical reddish. blue shade; of; the. alpha; phase products. It is crystal stable when exposed to organicv solventsyand'v it ishighly resistantto tlocculationY inz coating compositions. As; an alternative method forfparticlesize` reductiom. 10 parts-.ofthis crude pigment and.9 0, parts of sodium chloride are, charged to. a ballmill containing- 1600 parts. of

Y steel bars 1/zj indiarneter by 1f' long and of such a size that it is. slightly morer thaxrhalf` full when charged. The mixtureis milled. fora-bnut 36 hours, discharged from the mill and. extractedatthe; boil with aboutA 650 parts of dilute (45%-) sulfuric acid. Afterv filtering, washingkfreeaof soluble salts, dryingandi pulverizing, an intense` blue copper. phthalocyanine; pigment. obtained which. is?, crystal stable and flocculation resistant.v

Example lll The following ingredientsv are, charged to the reactor of Eixample I' Y 128 parts'phthalonitrile 35; 'parts'cupricA chloridel anhydrousv 0l7 part ammoniuml molybdate 6.0`partspyridine 3l0`part`sdeodori2edkerosene ,'Ihe-fmixture` isA heated with goed; agitation te' about 205916; over-a'vperiod-offaboutl hour andheld-at`2t'l5"v C.`-2.l0` C. for about 4 hours: It'i'sthenv cooled toA about C.' and addedtoA about'2000'parts of'water containing about V20 parts "ofsodium -hydroXide'to' givea kpH of about 10.0. 'fhi'semulsion-likemixture is heated` `to the boilunder good'agitation and then filtered and washed with hot water.'A Thewet solid, Whichstill con-- the-pigment is. extracted with.` 5%' sulfuricV acid. Afterl filtration,Y washing, drying, andipulver-izin'g; there is obtained a crystal-stable, occulation-resistant,f copper phthalocyanine pigment which Vcontains about 4% chlorine-and is-substantially all'in vthe alpha-crystalphase.

Afterl particle size: reduction byY 30 parts Yof thisl dry, partially milled.

Y 'Example IV The process of Example I is repeated except that 26 parts of cuprous chloride anhydrous is used as the sole source of copper. The product after acetone milling contains about 1.8% chlorine and comprises a mixture of about'` 20% beta phase and 80% alpha phase copper phthalocyanine. Nevertheless, it exhibits the overall color properties of an alpha phase pigment; it is crystal stable and resistant to occulation in coating compositions.

Example V (a) The procedure of Example I is followed except that 3.5 parts of quinoline is used in place of pyridine;

(b) 'Ihe procedure of Example I is followed except that 3.5 parts of isoquinoline is used in place of pyridine;

(c) The procedure of Example I is followed except that 2.5 parts of picoline is used in place of pyridine.

The resulting products from the above processes exhibit markedly improved nocculation resistance in comparison to products made by an otherwise similar process in the absence of the aromatic tertiary nitrogen bases.

Example VI 35 parts of cupric chloride anhydrous and 5 parts of pyridine are mixed in the absence of water. A vigorous reaction takes place whereby a solid copper pyridinium complex is formed which is pulverized and mixed with 128 parts of phthalonitrile and 128 parts of crystalline sodium chloride. This dry mixture is heated in an inert vessel Within an ovenV to about 200 C. whereupon a vigorous exothermic reaction tes place with the formation of a mixture of a chlorine-containing copper phthalocyanine and sodium chloride in approximately equal amounts.

For particle size reduction 116 parts of the crude pigment is, charged to a ball mill lled to about 40% of its volume with about 1000 parts of iron bars (li/ x 1"), milled for about 6 hours and discharged in dryform. 53 parts of this dry, partially milled product is then charged to a ball mill of the same size containing 1000 parts of l steel shot together with 140 parts of acetone and milled for about 12 hours. The slurry of pigment in acetone is discharged from the mill, the acetone is recovered by steam distillation and the pigment is extracted with sulfuric acid. After ltration, washing, drying and pulverizing, there is obtained a crystal-stable, occulation-resistant', chlorine-containing copper phthalocyanine of the alpha crystal phase.

This example is illustrative of thealternative embodiment which'prereacts the pyridine and the copper chloride. The other aromatic nitrogen bases suitable in this invention'may be Vprereacted in the same manner.

Example I is a preferred process which uses kerosene as the inert liquid diluent for the reaction. Example II shows trichlorobenzene as the liquid diluent, and Example VI uses no solvent at all but carries out the reaction in the fused state. The presence or absence of the solvent and the nature of the solvent appear to exert some inuence on the chlorine content of the product resulting from the reaction as described, and this point seems to be reected to some extent in the degree of flocculation resistance imparted by the process. How.-n ever, a substantial improvement in occulation resistance exists regardless of the nature of the solvent, and it is not contemplated that the nature of the solvent or its presence is at all critical to the improvement resulting from Ythis invention.-

All of the examples have shown the use or' unsubstituted phthalonitrile in the preparation of the pigment for the simple reason that copper phthalocyanine is the only metal phthalocyanine which has achieved widescale-'commercial use as a pigment. Nevertheless, substituted phthalonitriles such as 4chlorophthalonitrile, 47nitrophthalonitrile, tetrachlorophthalonitrile, 2,3-naphthodinitrile may be lused in this reaction, and where they are used, improvements in occulation resistance will relv sult from the use of a small amount of pyridine in the'` mixtures thereof will be determined largely by the desired chlorine content which should be kept between about 1.8% and 5% by weight. In every case, however, the chlorine content of pigments synthesized in the presence of the pyridine is significantly less than would be expected if the pyridine were not present. It is a very surprising part of this invention that, in spite of this markedly lower chlorine content, the products possess the crystal stability of the previously known crystal-stable alpha phase copper phthalocyanines of significantly higher chlorine content. In the lower amounts of this 1.8-5% range for chlorine, the milling operations which use solvents frequently result in the conversion of a small amount, and in some cases up to 20%, of the pigment to the beta crystal phase. However, it is a surprising fact that the tinctorial properties do not reflect this presence of upwards of 20%v of beta phase. Products made by this invention all show the relatively high strength and the relatively red hue characteristic of the alpha phase -copper phthalocyanine pigments.

Example V shows several aromatic tertiary nitrogen bases which are eifective for the purposes of this invention. However, pyridine is the preferred nitrogen base since it produces the most outstanding products. The amount of nitrogen base used is a critical feature of this invention. A range of .015 -mol to .l5 mol of nitrogen base per mol of phthalonitrile, which in the case of pyridine corresponds to approximately 0.9 part by weight to.9.0 parts by Weight per parts of phthalonitrile, has been found to produce occulation-resistant, crystalstable products. If amounts below this range are used, there is no significant improvement over products which are produced in the absence of the nitrogen base. Above the upper limit,` occulation resistance is not substantially affected, but tinctorial properties suier markedly and crystal stability is lessened as a result of a signiiicantly lower Vchlorine content., A preferred range of, nitrogen base'per mol of phthalonitrile is .025 to .075. The con-` ditions for the phthalocyanine synthesis'in the presence of the nitrogen base are substantially the same as they are for the well known processes of reacting an'o-arylene dinitrile, such as phthalonitrile, with a copperchloride. Such processes are disclosed in U.S. Patents 2,129,013 and 2,242,301, and the conditions comprise heating an o-arylene dinitrile and a copper chloride at a tempera? ture above C. but below the temperature at which the dinitrile will carbonize until a solid blue coloring matter is obtained. The temperature range is usually above about 180 C. and up to about 300 C., and a range of about C.-210 C. is preferred. In those syntheses which are carried out in a liquid diluent, temperatures up to 250 C. may be used. The time of reaction is usually at least l hour and preferably in the range' of 2 to 4 hours. The usual reacting proportions are 4 mols of o-arylene dinitrile to about 1 mol of copper chloride.

The manner of recovering the pigment from the reac-.

tion mixture is not critical to this invention, but the best results are obtained by following the procedure of Example I. The preferred separation process as disclosed in this example involves the reaction of the pigment in the presence of the liquid diluent with a concentrated sulfuric acid to form the sulfate which readily settles from the reaction slurry and makes it possible to decant most of the kerosene from the reaction mixture. The sulfate is then hydrolyzed by immersing it in an aqueous ing pigment to desired particle size is suitable.

`the phthalonitrile. synthesis is not well known.

alkaline saludan, and finally, the pigment isiextrated- Withan valkaline solution and iiltered, washed and; dried.

VThe sulfat'ion process is that shown in U.S. Patent 2,6?32,- Vt300 to Barnhart. The -alternative process of simply add` v ably leaves some of the pigment in the beta phase, be-

cause of the inuence of the solvent', and the conversion.

to alpha phase must be accomplished subsequently in the milling operation. This is, of course, easily done by Simple salt milling.. When trichlorobcnzene is used as the solvent, steam distillation is used to subsequently remove it, since the highv density ofthe liquid renders the decantation process ditiicult. within the knowledge of thc art and should be looked upon ais alternative and conventional.

Witlrrespect to the particle size reduction process, it is pointed out that the well known acid pasting process is not effective since, for some unknown reason, it appears to destroy the ilocculation resistance inherent in the crudes which are made by this process. Consequently,

it has been necessary, and'this is aV critical feature of Y theV invention, to carry out the particle size reduction by mechanical milling methods. Three alternatives are shown, but any of the mechanical methods for reduc- Pigment particle size for copper phthalocyanine pigments is usually regarded by the art as being less than 0.2'micron and Y may be familiar with ball millirrfy operations.

Salt millingafter the manner of U;S. Patent 2,402,167

is also useful as a finishing method. The pigment is Y ground in a ball mill using large balls or short bars as the grinding aid in the presence of several times its own weight of a water-soluble inorgauic'salt, such as sodiumV chloride. Again the details arenot critical, and the process is well understood by those'familiar with this field.

It is pointed out that some of the examples use a small amount ofv ammonium molybdate in the preparation. This material has been widely used as a catalyst inthe phthalic anhydride urea synthesis, but its use in This material is not necessary for the. accomplishment of the principal objectsrof this invention, but it does significantly improve the yields.

Since it is obvious that many changes and modifications can be madeV in the above-described details without departing from the nature and spirit of the invention, it is These variations Vare ail Y ing copper phthalocyanine coloring matters byV heating phthalonitrile and a copper chloride at atemperature above 180 C. Vbut below theY Vtemperature .at which phthalonitrile will carbonize until a Vb'lue solidY wcoloring, matter is obtainedthe improvement'which `comprises conducting said heating in the presence of from .0.15.7to

' .15 mol of an aromatic tertiary nitrogen bas'epermol to be understood that the invention is not to be limited to said details except as set forth in the appended claims.

I claim as my invention: l. In a process for the production of chlorinecontain ing copper phthalocyanine coloring matters by heating an o-arylene dinitrile and a copper chloride -at a tcmof phthalonitrile until Vthe blue solid coloring matter isv obtained, recoveringV said* coloring matter and reducingY it to pigment particle sizervbymechanical means and recovering a occulation-resistant,'crystal-stable, chlorinecontaining copper phthalocyanine pigment exhibiting the characteristics of the alpha crystal phase.V

3. In a process for the` production of chlorine-contain? ing copper phthalocyanine coloring matters by heating phthalonitrile and a copper chloride until a blue solid coloring matter is obtained, the improvement which comprises conducting said heating at a temperature' in the' range Vof 1809 C.'250 C. in the presence of from .015 to .15 mol per mol of phthalonitrile of an aromatic 'ter' tiary nitrogen base selected from the group consisting of pyridine, picoline, quinoline and isoquinoline until the blue solid coloring matteris obtained, recovering said coloring matter and reducing'V it to pigment particle size by mechanical'means and recovering a flocculation-resistant, crystal-stable, chlorine-containing ,copper phthalacyanine pigment exhibiting the characteristics of the alpha crystal phrase. Y

4. In a process for the production of chlorine-contain- YYing copper phthalocyaninejcoloring matters by heating phthalonitrile and a copper chloride in the presence of Va liquid diluent until a blue solid coloring matter is obtained, the in'rprovement which comprises conducting said heating at a temperature in theV rangeof Cf- 250 C. in the presence of from .015 to .15 mol per mol of phthalonitrile of an aromatic tertiary nitrogen base selected frornthe group consisting of pyridine, picoline, quinoline and isoquinoline until the blue solid coloring matter is obtained, krecovering said coloring matter and reducing it to pigment particle size by mechanical meansv and recovering a liocculation-resistant, crystal-stable, chlorine-containing copper phthalocyanine pigment exhibiting the characteristics of the alpha crystal phase.

5. The processof claim .4 in which the heating is carried out in the presence of from .025 to .075 mol of pyridine.

6. In a process for' the production of chlorine-containing copper phthalocyanine coloring matters by heating phthalonitrile, ammoniummolyb'clate, and a copper chlo'- ridein the presence of a liquid diluent until a blue solid coloring matter is obtained, the improvement which com prises conducting said heating'at a temperature in the range of 190 C..2l0 C. in the presence of from .025 to .075 mol of pyridine per mol of phthalonitrile until the blue solid coloring matter is obtained, reacting saidcoloring matter with sulfuric acid to produce a sulfation product, removing said liquid diluent, hydrolyzing said sulfation product in` anY aqueous alkaline solution. of suiiicient alkalinity to neutralize the mixture, Washing and drying the chlorine-containing copper phthalocyanine resulting from the aqueous treatment, ball milling the copper phthalocyanine thusV obtained in the presence of acetone to pigment particle size andrecovering a iloccu lation-resistant, `crystal-stable, .chlorine-containing copper phthalocyanine exhibiting Vthe tinctorial characteristics of the alpha crystal phase. A

7. A process for the production of occulation-resistant, crystal-stable, chlorine-containing copper phthalocyanine f pigment winch comprises commingling phthalonitrle, a

copper chloride and pyridine in the proportions of Aabout 1 mol of copper chloride to 4 mois of phthalonitrle and from .G15 to 0.15 mol of pyridine per mol of phthalonitrile,.heating the comrningled materials until a blue phthalocyanine is obtained, recovering said phthalocyanine and reducing it topigment particle size by mechanical means, and recovering a occulation-resistant, crystalstable, chlorine-containing phthalocyanine pigment exhibiting the tinctorial characteristics of the alpha crystal phase.

8. The process of claim 7 in which the copper chloride and pyridine are premixed before being commingled with the phthalonitrile.

9. A process for the production of occulation-r sistant, crystal-stable, chlorine-containing copper phthalocyanine pigment which comprises reeacting by commingling copper chloride and pyridine, then commingling the reaction product thus obtained with phthalonitrile, the commingling proportions being about 1 mol of copper chloride to 4 mols of phthalontrile and about .015 to 0.15 mol of pyridine per mol of phthalonitrile, heating the commingled reaction product and the phthalonitrile until a blue phthalocyanine pigmentary material is obtained, ball milling said pgrnentary material in the complete absence of liquid, subsequently ball milling in the presence of acetone and recovering a occulation-resstant, crystal- References Cited in the le of this patent UNITED STATES PATENTS 2,129,013 Linstead v.. Sept. 6, 1938 2,302,612 Lacey Nov. 17, 1942 2,318,787 Lacey May 1l, 1943 2,615,027 Bluemmel et al Oct. 2l, 1952 2,826,589 Muehlbauer et al Mar. l1, 1958 FOREIGN PATENTS 741,251 Germany Nov. 81943 410,814 Great Britain May 16, 1934 761,718 Great Britain Nov. 21,1956

OTHER REFERENCES F.I.A.T. Final Report No. 1313, Vol. III, p. 346 (1948). 

1. IN A PROCESS FOR THE PRODUCTION OF CHLORINE-CONTAINING COPPER PHTHALOCYANINE COLORING MATTERS BY HEATING AN O-ARYLENE DINITRILE AND A COPPER CHLORIDE AT A TEMPERATURE ABOVE 180*C. BUT BELOW THE TEMPERATURE AT WHICH THE DINITRILE WILL CARBONIZE UNTIL A BLUE SOLID COLORING MATTER IS OBTAINED, THE IMPROVEMENT WHICH COMPRISES CONDUCTING SAID HEATING IN THE PRESENCE OF FROM .015 TO .15 MOL OF AN AROMATIC TERTIARY NITROGEN BASE PER MOL OF O-ARYLENE DINITRILE UNTIL THE BLUE SOLID COLORING MATTER IS OBTAINED, RECOVERING SAID COLORING MATTER AND REDUCING IT TO PIGMENT PARTICLE SIZE BY MECHANICAL MEANS AND RECOVERING A FLOCCULATION-RESISTANT, CRYSTAL-STABLE, CHLORINE-CONTAINING COPPER PHTHALOCYANINE PIGMENT EXHIBITING THE CHARACTERISTICS OF THE ALPHA CRYSTAL PHASE. 